10.5061/DRYAD.PC866T1QM
Crossland, Michael
0000-0001-9967-7158
University of Sydney
Shine, Richard
Macquarie University
DeVore, Jayna
University of Sydney
Toxin cues affect cannibalism responses of cane toad tadpoles
Dryad
dataset
2022
FOS: Biological sciences
Australian Research Council
https://ror.org/05mmh0f86
FL120100074
2023-01-27T00:00:00Z
2022-03-17T00:00:00Z
en
https://doi.org/10.1002/ece3.8655
67004 bytes
4
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
In many species cannibalism is uncommon and involves non-selective
consumption of conspecifics as well as heterospecifics. However, within
their invasive Australian range cane toad larvae (Rhinella marina)
specifically target and voraciously consume the eggs and hatchlings of
conspecifics, often extirpating entire clutches. In contrast, toad larvae
rarely consume the eggs and hatchlings of native frogs. Here, we use
laboratory studies to demonstrate that this selective consumption is
triggered by species-specific chemical cues: maternally-invested
bufadienolide toxins that otherwise defend cane toad eggs and hatchlings
against predators. We find that these cues stimulate feeding behaviors in
toad tadpoles, such that the addition of bufadienolide toxins to the water
column increases predation on eggs, not only of conspecifics, but also of
native anuran species that are otherwise usually ignored. In contrast, we
find that cannibalism rates on conspecific hatchlings are high and
unaffected by the addition of bufadienolide cues. The maternally-invested
toxins present in conspecific eggs may therefore be more easily detected
post-hatching, at which point tadpole feeding behaviors are induced
whether or not additional toxin cues are present. As bufadienolide cues
have previously been found to attract toad tadpoles to vulnerable
hatchlings, our present findings demonstrate that the same toxin cues that
attract cannibalistic tadpoles also induce them to feed, thereby
facilitating cannibalism through multiple behavioral effects. Because
native fauna do not produce bufadienolide toxins, the species-specificity
of these chemical cues in the Australian landscape may have facilitated
the evolution of targeted (species-specific) cannibalism in invasive cane
toad populations. Thus, producing bufadienalide toxins confers a cost
(increased vulnerability to cannibalism in early life-stages) as well as a
benefit (reduced vulnerability to predation by other taxa).
The data are from a series of laboratory experiments conducted in
Australia, where eggs/hatchlings of invasive cane toads (Rhinella marina)
and a native frog (Litoria tornieri) were exposed to a predatory cane toad
tadpole in the absence versus presence of toxin (bufadienolide) cues. The
response variable was the number of eggs/hatchlings consumed. Data were
analysed as a binomial response to treatment.
The data provided are the raw data as collected during the experiments.
When we analysed the data, there were several instances where the models
failed to reach convergence due to 100% survival in the Control treament.
To account for this and obtain a conservative estimate of effect, we
allocated one tadpole to have died in the Control treatment. Specifically,
we did this for: Experiment 1 C. albogutata (TadPresent versus TadAbsent),
P. ornatum (TadPresent versus TadAbsent), R.marina (TadPresent versus
TadAbsent) Experiment 2 Egg stage 14 analysis (toxin absent versus
present). Details of these adjustments are given in our manuscript and in
the attached README file. To follow our analyses in these specific
instances, others need to make these adjustments. Also, note that the data
sheet "Expt 2 Toad Egg-Hatchling Data" has data for both number
of eggs eaten/not eaten and number of hatchlings eaten/not eaten. Thus,
while eggs were developing and not yet hatched in this data set, the
columns for TotalNSurvivingAtHatching, HatchlingsEaten and
HatchlingsNotEaten are not relevant because eggs have yet to reach the
hatchling stage (i.e., there are no hatchling data). In these instances,
the cells for TotalNSurvivingAtHatching, HatchlingsEaten and
HatchlingsNotEaten are filled with "n/a" (not applicable).